Monday, July 23, 2012

Our final focus on filters for digital camera lenses consist of both cooling and warming filters. Both are
used to change the white balance. For those who do not know, white
balance is a process to remove unrealistic color casts. Ever notice a
blue tinge on compact camera photographs? That's because the white
balance is off. Besides correcting color cast, the filters can also
be used to add unrealistic color –which is more the case
nowadays.

Thanks to automatic white balance
adjustment and photo editing programs, the filters aren't often used
to correct a photo. Certain situations, though, may call for their
use such as unusual lighting or underwater photography. White balance
cannot restore color when there is a large amount of monochromatic
light and if it does, you can expect a big amount of image noise.

A colored filter will either lighten or
darker opposite colors. For example, a red filter will darken green
and blue. You can even use colored filters when taking black and
white photography. Many colors look very similar when converted into
grayscale. This will leave you with flat photographs that lack any
contrast. A color filter will let in its own color of light and block
out the rest. The result will be colors matching the filter will
appear brighter while the other colors will appear darker. Obviously
in black and white photography that means lighter or darker shades of
gray –making images more dramatic.

Monday, July 16, 2012

Unlike other camera filters that
somehow alter the image, UV filters are primarily used to protect the
camera lens. They are clear and do not affect the image. With film
cameras, however, they can actually reduce haze and improve contrast
because they limit the amount of UV light that reaches the film. UV
light may not be visible to the human eye but on a hazy day, it will
reduce film contrast. For digital photographers, this isn't much of
an issue because a digital camera sensor is not as sensitive to UV
light as film.

If you opt to use the filter on a
digital camera, for protection purposes, be aware that they have the
potential to decrease image quality because they increase lens flare.
The filter will either reduce contrast or add a slight color tint. To
combat this potential problem, choose a multi-coated UV filter and
keep the filter very clean. And of course, pick high quality brands.

There is often debate whether
photographers need the filter for protection, considering the
potential degradation of image quality. Often those with rather
expensive SLR lenses use one because it's cheaper to replace a filter
than a lens. Personal preference ends up being the determining factor
for people with less expensive lenses.

Monday, July 9, 2012

Last week we gave an overview of
neutral density filters, but today's focus will be graduated neutraldensity filters –which are actually different from their relatives.
As the title of the post suggests, they are an essential addition for
landscape photographers. Our eyes naturally adjust to varying
brightness levels, but a camera captures the scene with the same
exposure, causing bright and dark regions to be null of detail and/or
washed out. With a GND filter the camera can capture the photo how we
see it.

The effect is achieved by pushing more
light toward one side of the filter. It is ideal when brightness
uniformly changes in one direction, such as a horizon. The wider the
angle of view, the more enhanced the picture. They are called
graduated because they have a graduated blend. The blend goes
from clear to neutral gray, and the density of gray increases,
blocking more light.

GND filters are categorized by their
strength and rate of transition. The strength refers to the
difference between how much light is reduced at one side compared to
the other. Transition refers to the rate at which the darkest side of
the filter transitions into the clear side.

Thursday, July 5, 2012

Neutral density filters are one of the
most popular filters for digital camera lenses. They are able to
reduce the amount of light entering the camera, which allows for a
longer exposure time. The longer exposure time will emphasize motion,
making the scene seem almost surreal. The surreal effect is often
witnessed on photographs of moving water, like rivers and waterfalls.
The filter can create tempestuous water and blurred motion –whether
the subject is people, moving cars, or blowing grass.

Other effects are a shallower depth of
field and a sharper image, both ideal qualities. While the filter is
not as commonly used for these applications, they are still
beneficial. The filter works well in very bright light to enable a
shallow depth of field, resulting in background blur and isolation of
the subject.

How does the filter work? It is
actually just a piece of semi-transparent glass that inhibits a
controlled fraction of incoming light uniformly, meaning it does not
alter the image contrast or sharpness. Because it's equal across the
visible spectrum, it also does not introduce color cast, which gives
the filter its name neutral. The filters are categorized by
the strength of their light-reducing ability. Stronger filters are
darker shades of gray.